Core disintegrating drill bit



March 21, 1961 w, STUART 2,975,849

CORE DISINTEGRATING DRILL BIT Filed April 25, 1958 2 Sheets-Sheet 1 P. W. \Sfuarf INVENTOR.

ATTORNEY March 21, 1961 w STUART CORE DISINTEGRATING DRILL BIT 2 Sheets-Sheet 2 Filed April 25, 1958 R. V\/. J/uar/ INVENTOR.

BY $8 1M ATTORNEY United rates l atent G F CORE DISINTEGRATING DRILL BIT Robert W. Stuart, Midland, Tex., assignor to Diamond Oil Well Drilling Company, Midland, Tex a corporation of Texas Filed Apr. 25, 1958, Ser. No. 731,025

5 Claims. (Cl. 175-333) This invention relates to the drilling of holes in the earth and more particularly to the cutting of a passage through rock formations, as is done to reach deep oil and gas deposits.

Conventional well drilling equipment includes a derrick and a rotary table at the ground surface for suspending and rotating a string of pipe terminating in a -Drill string rotation much above sixty revolutions per minute generally is considered too fast because the cutting tips of a toothed bit tend to roll over without breaking into the surface. Bits having a diamond faced ring to drag on and grind or abrade the formation are often used in obtaining a formation sample in the form of an uncut central core but the rate of penetration is relatively slow at customary drilling speeds within practical limits to avoid objectionable rotational whipping of a long drill string with attendant violent and harmful wobble slapping against the bore wall and drilling direction disturbance. Other than for sampling purposes, diamond bits have had very little use.

Well drilling attempts with a rotary disk faced throughout its diameter with abrasive cutting diamonds is impractical, partly because the abrading area is greater and runs at higher peripheral speeds the farther away from its zero velocity center. However, I have found that a high penetration rate can be had with a grinding ring to operate in a circular path centrally spaced a short distance from the rotational axis when combined with an effective crusher for breaking down the narrow formation area within the central region of the grinding ring and with properly designed drilling fiuid courses to rid the bit quickly of cuttings and without dependence on drill string rotation and that bit speed can be in excess of seven hundred fifty revolutions per minute and as much as two thousand revolutions per minute under loads ranging from five hundred pounds per square inch for large bits to about one hundred pounds per square inch for smaller bits.

An object of the present invention is to provide improved drilling equipment capable of effective operation at rotational speeds many times the rate to which conventional rotary toothed bits are limited and for more quickly penetrating rock formations with fewer drill string trips in and out of the hole for changing Worn bits.

Another object of the invention is to employ a nonrotating pipe string which is free from whipping force and delivers pressure fluid to a drive motor and high speed abrasive bit assembly at the lower end of the pipe string for first impinging the pressure fiuid on and driving the motor rotor and the bit connected thereto and then ice 2. passing on to absorb drill generated heat and to flush away and entrain cuttings for return to the surface.

Other objects and advantages will become apparent during the course of the following specification having reference to the accompanying drawing wherein Fig. 1 is a view partly in vertical section and partly in side elevation of a drive motor and bit assembly in a well hole; Fig. 2 is a vertical section on a larger scale of the drill bit in operative position, the section being taken on line 22 of Fig. 3; Figs. 3 and 4 are transverse sections on lines 33 and 4-4, respectively, of Fig. 2; and Fig. 5 is a bottom plan view in the direction of the arrows on line 5-5 of Fig. 2.

In the drawings the main tool body 1 of the bit consists of a hollow steel cylinder having a central partition 2 dividing the interior of the body into an upper internally screw threaded chamber and a bottom crusher containing chamber or pocket opening through the lower end of the body 1. Pocketed within the upper portion of the lower chamber are a pair of toothed conical rollers 3 with carbide or hardened tips. They are mounted for free rotation on a transverse axis afforded by a shaft 4 which extends across the chamber and has its opposite ends fitted into aligned openings in the chamber wall. A locking pin 5 extends through the wall of the body 1 and the pin 4 for anchoring these parts in assembly. The combined axial length of the two rollers 3 approximates the internal diameter of the lower chamber and the inner faces of the rollers about one another in a plane that intersects the vertical rotational axis of the body 1 and thus turn oppositely one to the other with bit rotation.

At its lower end the annular wall of the body 1 is screw threaded both internally and externally. After the rollers 3 are inserted into the upper end of the chamber, an externally threaded guide collar 6 is fitted and threaded into the internal threads of the body and provides a.

,liner or guide surface for the central rock formation support for the rock column 7 when the crusher rolls 3 rest and act on the top face of the column and place thrust load on the relatively thin column. The lateral bearing support minimizes the likelihood of the column breaking or fracturing at a distance below the working face and which possibly could foul up the smoothness of bit operation.

Engaged 'with the external threads at the bottom of the body 1 is an upstanding skirt of an annular drilling ring 8 inclusive of a bottom annular Wall of increased external and decreased internal diameters and provided with surface grooves or watercourses it) across its inner, outer and lower faces at circularly spaced apart intervals. For convenience of manufacture, the widened and grooved end portion may be separately formed and welded on the under side of the upper portion of the drilling ring assembly as a terminal nose piece Whose bottom face and inner and outer faces have embedded therein a large number of diamonds which protrude slightly from the faces for digging into the rock formation beneath and laterally of the drill bit. The formation is thus abraded or ground in the annular path of the abrasive ring 8. The central aperture in this ring is of a diameter which determines thickness of the upstanding core column 7 and substantially corresponds with the diameter of the guide ring 6 so that the uncut central portion of the formation is received through the center aperture and is laterally braced against side thrust and rupture by the guide ring 6 in the region immediately below its relatively small upper face area presented for action thereon by the crushing rolls 3. By way of example, balance crushthe cuttings, the'diamond cutting face preferably is provided with a series of radial grooves or watercourses 10. These watercourses extend downwardly on the in side of the drilling ring 8 from a manifolding chamber 11 in the body 1 just below the guide collar 6. The

chamber 11 receives drilling liquid under pressure of about two hundred pounds per square inch from a series of bored passageways 12 extending downwardly from the .lower end of the upper chamber above the partition 2.

The internal bearing surface of the guide collar or ring 6 preferably is formed with a series of axial grooves or watercourses13, as seen in Fig. 4, providing lands therebetween and insuring clearance for reverse or upward flow of the drilling liquid from the manifold chamber 11. Usually guide collar clearance around the formation column will be such that a circular flowing film or wall of pressure liquid surrounds the formation spindle 7 and maintains yieldable high pressure fluid force radially against the column surface to augment the internal bearing surface of the guide collar 6 for bucking against fracturing strain below the top column face being acted on by roller crushers 3.

Additional jet passages, as at 22, extend downwardly through the intermediate horizontal partition 2 from the upper chamber and are arranged to discharge high velocity liquid streams against the uppermost tooth spaces of the rollers 3 for dislodging cuttings from and eliminating clogging of the working teeth. The flowing liquid, both that directed into the chamber by the jet passages 22 and that rising upwardly through the guide collar -6, carries along loose cuttings and leaves the top of the chamber through one or more outlet ports 14 extending outwardly through the chamber wall. The volume and velocity of the liquid flow through the crusher chamber keeps the chamber space clear by immediately removing cuttings and preventing balling up and accumulations to interfere with crushing operations.

The upper end of the body 1 is mounted by a threaded joint on a hollow spindle 15 which constitutes the drive shaft of the motor assembly. This shaft is rotatably mounted by bearings 16 in a housing 17 whose upper end is joined to the lower end 18 of a string of drill pipe. As in conventional well drilling practice, the upper end of the drill string 18 is suspended by a suitable derrick and will be engaged by the rotary table for making up joints but otherwise and during actual drilling, is held against rotation. Mud pumps deliver drilling fluid into the top of the drill string at high pressure and the pressure fluid is supplied into the top of the hollow motor housing 17. In the upper portion of the housing 17 is located a varied stator 19 which imparts a swirling direction to the liquid stream and the directed high velocity liquid then impinges on a rotor 20 fixed to the hollow shaft 15 and having shaped buckets or vanes for transmitting liquid force to spin the drive shaft 15. The arrangement of the fluid motor is selected for rotational speed in excess of seven hundred fifty revolutions per minute for effectively drilling with diamond bits; The drilling fluid after passing through the motor rotor 29 leaves the housing 17 through lateral windows 21 in the wall of the hollow shaft 15 above the bearing 16 for flow downwardly to the distributing passages 12 and 22. Ex-

cept for the small fraction going to the cleaning jets 22,

the liquid is led by the several passages 12 into the manifold chamber 11 and distributes downwardly by the several face grooves 10, washing over the grinding area and returning with cuttings upwardly by way of the open hole. Back pressure below the manifold chamber 11 directs about ten percent of the fluid upwardly around the upstanding column '7 and into the crusher chamber in reverse to and for combining with the downwardly Li directed jet streams for cooling the crushers and flushing chips and cuttings upwardly away from regrinding contact with the lower bit grinding face and out through the ports 14 into the rising bore hole stream.

A preferred embodiment of the invention has been described specifically and it may be modified within the scope of the appended claims.

What is claimed is:

1. In a rotary drilling bit of the character described, a body having a downwardly open central pocket and a lateral discharge port leading from the upper end of said pocket and opening to the exterior of said body, rotary crusher means journaled within the upper end of said pocket, a centrally open downwardly facing grinding ring on the underside of said body, a core guiding annular insert lining the lower portion of said pocket below said rotary crusher means and extending in axial alignment with the central opening in the grinding ring said body having a hollow coupling portion at the top thereof providing an entry passageway for drilling fluid under pressure and terminated downwardly in branch passages, one of which passages opens into said pocket as a cleaning pressure stream directing jet aligned with said rotary crusher means above the working region thereof and another of which passages opens into said pocket in a region intermediate said rotary crusher means and said grinding ring and arranged for co-operation with a core formed during a grinding operation and projected into said central pocket for directing drilling fluid downwardly to said grinding ring and upwardly as an annular fluid wall between the core and the annular guide member and for exhaust from the upper end of the pocket through said lateral discharge port.

2. In a rotary drilling bit of the character described, a main body having a drive coupling upper portion con taining a passage for pressure drilling fluid and a drilling head lower portion containing a hollow chamber open at its lower end and branch passages leading from the passage in said upper portion and terminating at discharge outlets into said chamber intermediate its vertical length and said body also having an outlet passage leading from the upper portion of the chamber and opening to the exterior of said body, an annular grinding bit facing downwardly on said drilling head and having a central opening aligned with said hollow chamber for the passage downwardly of the chambered body about a central core of the material being ground during bit operation, core crusher means mounted by the head interiorly of the upper part of said chamber and an annular guide bearing inserted within the chamber below said crusher means and above the outlets of said branch passages for guide bearing relation with a core and for confining and directing a portion of the drilling fluid discharged into the chamber for flow upwardly to said outlet passage and between the annular guide bearing and a core surrounded by the bearing.

3. In a rotary drilling bit as in claim 2, wherein said annular guide hearing has a'series of internal axially extending grooves to promote the upward flow of drilling fluid.

4. In a rotary drilling bit, a body having a transverse partition and a downwardly extended annular wall projecting below said partition and co-operating therewith to form a downwardly opening core receiving central pocket, means in the upper end of said body to receive pressure liquid, an abrasive ring secured to the bottom of said annular wall and centrally apertured in axial continuation of the pocket, an internal annular chamber in the wall adjacent the lower end of said pocket and above said abrasive ring, a core crusher roll rotatably mounted by said annular wall in the upper end of said pocket, a core guiding and stabilizing sleeve mounted on and internally lining said annular wall in a region projected upwardly above said annular chamber to a point immediately below the crusher roll and of an inside diameter substantially corresponding with the diameter of the central aperture of the abrasive ring, means for directing a pressure jet stream from the upper liquid receiving means and against said crusher roll and comprising a passage through said partition, said annular wall having a liquid flow channel leading from said liquid receiving means and into the annular chamber for liquid flow from the chamber downwardly through the abrasive ring and upwardly within said guide sleeve to co-operate therewith in core stabilization and to join with liquid directed through the partition passage and means comprising an outlet port leading from the pocket above said guide sleeve and through said annular wall for liquid exit to the outside of said body.

5. A drill bit as in claim 4 wherein the internal face 6 of the guide sleeve contains axially extending flow grooves.

References Cited in the file of this patent UNITED STATES PATENTS 1,482,397 Hansen Feb. 5, 1924 1,723,330 Cross et a1 Aug. 6, 1929 2,034,073 Wright Mar. 17, 1936 2,353,534 Yost July 11, 1.944 2,626,780 Ortlofi' Jan. 27, 1953 2,660,402 Devine et a1. Nov. 24, 1953 2,727,729 Boice Dec. 20, 1955 2,738,166 Koch Mar. 13, 1956 

